Non-Financial Assets Measured at Fair Value on Nonrecurring Basis (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended				12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Jun. 30, 2011	Mar. 31, 2011	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Investment in real estate	$ 300	$ 94,351			$ 300	$ 94,351
Notes receivable
Total Assets		94,351				94,351
Impairment of real estate					2,551	377,270
Impairment of notes receivable						55
Impairment charges	2,551	374,846	1,697	782	2,551	377,325	4,799
Level 3
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Investment in real estate	300	93,127			300	93,127
Notes receivable
Total Assets		93,127				93,127
Level 2
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Investment in real estate		1,224				1,224
Notes receivable
Total Assets		$ 1,224				$ 1,224